A diketopyrrolopyrrole dimer fluorescent material and a preparation method thereof

Abstract

The application discloses a pyrrolopyrrolopyrazine dimer fluorescent material and a preparation method thereof. Oxalic acid diester, amine and o-methoxybenzaldehyde are used as raw materials, a monoimide intermediate is synthesized through cyclization, reduction and hydroxyl protection and the like, and finally, the pyrrolopyrrolopyrazine dimer is prepared from the monoimide intermediate and aromatic dicyan under the catalysis of a strong base, and the pyrrolopyrrolopyrazine dimer has the characteristics of simple synthesis steps, mild conditions, easy structural modification and functional regulation, high molar extinction coefficient and large Stokes shift. Due to the presence of butyl, the fluorescent material molecule has good solubility without N-alkylation reaction, in addition, N-H in the molecular structure is convenient for subsequent functionalization, and the problems of single DPP dye structure, limited types of functional groups and difficult emission wavelength regulation are solved.

Description

Technical Field

[0001] This invention belongs to the field of organic small molecule fluorescent materials, and relates to a pyrrolopyrrole dione dimer fluorescent material and its preparation method. Background Technology

[0002] Pyrrolopyrrole diones (DPPs) are an important class of synthetic dyes, possessing advantages such as vibrant colors, excellent photostability, and thermal stability. In recent years, as electron acceptor units, DPP-based conjugated molecules and polymers have been widely applied in research across numerous fields, including organic field-effect transistors, organic photovoltaic devices, organic thermoelectrics, singlet splitting, and photodynamic therapy. The synthesis of DPP typically employs the classic cyclocondensation method: using diester (e.g., dimethyl succinate) and aromatic / heteroaromatic nitrile (e.g., benzonitrile, thiophenecarboxynitrile) as raw materials, the reaction is carried out under strong base catalysis (e.g., potassium tert-butoxide) in a high-boiling-point solvent (e.g., tert-amyl alcohol) under reflux, followed by bimolecular cyclization and dehydration to construct the DPP core framework.

[0003] There are several ways to chemically modify DPP: (1) N-alkylation: long-chain alkyl groups (straight-chain or branched substituents) are used to replace NH protons, which significantly improves the solubility of the material in organic solvents and is a prerequisite for preparing solution-processable polymers; (2) N-arylation: copper or palladium is used to catalyze coupling reactions to introduce aryl groups to replace NH protons, thereby regulating the molecular energy level and giving it excellent luminescence properties; (3) 3,6-position skeleton derivatization substitution: aryl / heteroaryl (phenyl, thiophene, furan, pyridine) units are introduced at the 3,6 positions through electrophilic substitution or coupling reactions to extend the π-conjugated system, red-shift the absorption / emission wavelength, and regulate the band gap; (4) carbonyl activation extension: carbonyl groups are used to condense with heterocyclic aromatic amines or heterocyclic aromatic acetonitrile compounds and to complex with B atoms to construct pyrrolopyrroloaza BODIPY. Or pyrrolopyrrolic cyanine compounds, further redshifting the spectrum to the near-infrared region for use in bioimaging or photodynamic therapy; (5) Introduction of side chain functional groups: Modifying the ends of alkyl side chains with azide, free radical (such as TEMPO), cyano, etc., to endow the material with optical patterning ability, improve n-type doping efficiency, or reduce LUMO energy level to enhance air stability. Although the research on DPP dyes has made great progress, it mainly focuses on the functionalization and derivatization of symmetrical DPP monomers, which has shortcomings such as many synthesis steps, harsh reaction conditions, low yield, and small Stokes shift, which limit the practical application of this type of dye in different fields. Therefore, it is of great significance to develop a DPP fluorescent material with a well-defined structure, simple synthesis, and large Stokes shift.

[0004] As novel building blocks of conjugated molecules and macromolecules, the synthesis of conjugated extended DPP dimer derivatives is rarely reported, and is limited by specific substrate structures and the need for multi-step reactions. This invention employs a novel strategy: using oxalate diester, amine, and benzaldehyde as raw materials, a monoimide intermediate is synthesized through reactions such as cyclization, reduction, and hydroxyl protection. Finally, a pyrrolopyrrole dione dimer is prepared with an aromatic dinitrile under strong base catalysis. Through structural optimization using this strategy, the absorption / emission wavelengths are controlled and the Stokes shift is increased. Due to the presence of the butyl group, the dye molecule exhibits good solubility without N-alkylation, and the NH group in the molecular structure facilitates subsequent functionalization. This solves the problems of DPP dyes having a single structure, limited types of functional groups, and difficulty in controlling the emission wavelength. Summary of the Invention

[0005] The purpose of this invention is to provide a pyrrolopyrroledione dimer fluorescent material, the structural formula of which is shown below:

[0006] , .

[0007] The preparation process of pyrrolopyrroledione dimer fluorescent materials is as follows:

[0008] .

[0009] Its preparation method includes the following steps:

[0010] (1) Add o-methoxybenzaldehyde and 2-5 times the amount of n-butylamine to a reaction flask, add alcohol solvent, react at room temperature for 1-2 h, then add 2-4 times the amount of sodium diethyl oxaloacetate and 3-5 times the amount of acid, react at 40-80℃ for 10-20 h, after the reaction is complete, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, distill under reduced pressure to obtain crude product, and purify to obtain intermediate 1;

[0011] (2) Add intermediate 1 and 3-5 times the amount of reducing agent to the reaction flask, add a mixed solvent of ethanol and acetic acid, and heat to 50-80℃ for 2-4 hours. After the reaction is complete, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain crude product. Purify to obtain intermediate 2.

[0012] (3) Add intermediate 2 and 2-4 times the amount of triethylamine to the reaction flask, then add dichloromethane, mix well, and slowly add 2-4 times the amount of trimethylchlorosilane. React at room temperature for 3-5 hours. After the reaction is complete, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain the crude product. Purify to obtain intermediate 3.

[0013] (4) Add 3 to 6 times the amount of base and 2 to 4 times the amount of aromatic cyano compound to the intermediate. The tert-amyl alcohol was added separately to the reaction flask, mixed thoroughly, and then heated to 60-100°C under nitrogen protection for 5-12 hours. After the reaction was complete, the mixture was cooled to room temperature, extracted with dichloromethane, the organic layers were combined, dried with anhydrous sodium sulfate, and the crude product was obtained by vacuum distillation. The crude product was purified to obtain DPP-dimer.

[0014] Preferably, the alcohol solvent in step (1) is selected from isopropanol, methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol.

[0015] More preferably, the alcohol solvent in step (1) is ethanol.

[0016] Preferably, the acid in step (1) is selected from formic acid, acetic acid, propionic acid and butyric acid.

[0017] More preferably, the acid in step (1) is acetic acid.

[0018] Preferably, the reducing agent in step (2) is selected from one of NaBH4, zinc powder, Pd / C, and LiAlH4.

[0019] More preferably, the reducing agent in step (2) is zinc powder.

[0020] Preferably, the alkali in step (4) is selected from lithium tert-butoxide, sodium tert-butoxide, NaH, and LiOH.

[0021] More preferably, the base in step (4) is lithium tert-butoxide.

[0022] As can be seen from the above technical solution, compared with the prior art, the present invention provides a pyrrolopyrrole dione dimer fluorescent material and its preparation method, which has the following beneficial effects:

[0023] 1. Unlike the classic stepwise coupling method for preparing pyrrolopyrrole dione dimers, this invention adopts a new synthetic strategy, which has the characteristics of well-defined structure, simple synthesis, concise steps, mild conditions and simple post-processing.

[0024] 2. This type of pyrrolopyrrole dione dimer fluorescent material has good solubility and large Stokes shift.

[0025] 3. This type of pyrrolopyrrole dione dimer fluorescent material is easy to modify in structure and modulate in function, providing an ideal platform for subsequent functional expansion. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 The normalized UV absorption spectra of the m-DPP-dimer prepared in Example 1 and the p-DPP-dimer prepared in Example 2 are shown below. The concentration prepared was 1*10 -6 mol / L, with tetrahydrofuran as the solvent.

[0028] Figure 2 The normalized fluorescence spectra of the m-DPP-dimer prepared in Example 1 and the p-DPP-dimer prepared in Example 2 are shown below, with a concentration of 1*10⁻⁶. -6 mol / L, with tetrahydrofuran as the solvent. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] Synthesis of Intermediate 1

[0032]

[0033] o-Methoxybenzaldehyde (2.72 g, 20 mmol), n-butylamine (4.38 g, 60 mmol), and 60 mL of ethanol were added to a 250 mL round-bottom flask and reacted at room temperature for 1.5 h. Then, sodium diethyl oxaloacetate (12.60 g, 60 mmol) and acetic acid (4.80 g, 80 mmol) were added, and the mixture was reacted at 60 °C. o The reaction was carried out at C for 18 hours. After the reaction was completed, the mixture was cooled to room temperature and extracted three times with dichloromethane. The organic layers were combined, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain the crude product. The crude product was recrystallized (ethyl acetate as a good solvent and petroleum ether as a poor solvent) to give 4.53 g of white solid intermediate 1, with a yield of 68%. 1HNMR (500 MHz, CDCl3) δ 8.78 (s, 1H), 7.39-7.28 (m, 1H), 7.08-6.76 (m, 2H), 5.84 (s, 1H), 5.20 (s, 1H), 4.13 (m, 2H), 3.92 (s, 3H), 3.73 (m, 1H), 2.64 (m, 1H), 1.54-1.41 (m, 2H), 1.26 (m, 2H), 1.07 (t, 3H), 0.85 (t, 3H).

[0034] Synthesis of intermediate 2

[0035]

[0036] Intermediate 1 (3.33 g, 10 mmol) and zinc powder (2.60 g, 40 mmol) were weighed and added to a 100 mL round-bottom flask. 20 mL of ethanol and 20 mL of acetic acid were added to the flask, and the mixture was heated to 70 °C and reacted for 3 hours. After the reaction was complete, the mixture was cooled to room temperature and extracted three times with dichloromethane. The combined organic layers were dried over anhydrous sodium sulfate and distilled under reduced pressure to give 2.85 g of white solid intermediate 2, with a yield of 84.9%. 1 H NMR (500 MHz, DMSO-d6) δ 7.32 (m, 1H), 7.19 (m, 1H), 7.07 (d, 1H), 7.02 (t, 1H), 6.03 (d, 1H), 4.94 (s, 1H), 4.35 (m, 1H), 4.14-4.01 (m, 2H), 3.78 (s, 3H), 3.47 (m, 1H), 2.85 (s, 1H), 2.43-2.41 (m, 1H), 1.25 - 1.14 (m, 4H), 1.12 (t, 3H), 0.78 (t, 3H).

[0037] Synthesis of intermediate 3

[0038]

[0039] Intermediate 2 (3.35 g, 10 mmol), triethylamine (3.03 g, 30 mmol), and 60 mL of ultradry dichloromethane were weighed and added to a 250 mL reaction flask. Trimethylchlorosilane (3.26 g, 30 mmol) was then added dropwise, and the reaction was carried out at room temperature for 4 hours. After the reaction was complete, the mixture was extracted three times with dichloromethane. The combined organic layers were dried over anhydrous sodium sulfate and distilled under reduced pressure to give 3.50 g of yellow oily intermediate 3, in 84.9% yield. 1H NMR (500 MHz, CDCl3) δ 7.37-7.25 (m, 1H), 7.20-7.16 (m, 1H), 6.96 (m, 1H), 6.91 (t, 1H), 5.09 (m, 2H), 4.58 (d, 1H), 4.16 (m, 2H), 3.81 (s, 3H), 3.65 (m, 1H), 2.50 (m, 1H), 1.35 (m, 2H), 1.21 (t, 3H), 1.17-1.13 (m, 2H), 0.82 (t, 3H), 0.19 (s, 9H).

[0040] Synthesis of m-DPP-dimer

[0041]

[0042] Lithium tert-butoxide (4.00 g, 50 mmol) was weighed and added to a 100 mL round-bottom flask. The flask was purged with nitrogen three times. Then, isophthalonitrile (3.84 g, 30 mmol), intermediate 3 (4.07 g, 10 mmol), and 20 mL of tert-amyl alcohol were added. The mixture was heated to 80 °C and reacted for 10 h. After the reaction was complete, the mixture was cooled to room temperature, and 20 mL of acetic acid was added with stirring. The mixture was extracted three times with dichloromethane, and the organic layers were combined. The extract was dried over anhydrous sodium sulfate and distilled under reduced pressure to obtain the crude product. The crude product was purified by recrystallization to give 3.78 g of an orange-red solid product (m-DPP-dimer), with a yield of 54%. MS (ESI): m / z [M] + calcd for C 40 H 38 N4O6: 670.284, found: 670.282. Elemental Analysis calcd: C, 71.63; H, 5.71; N, 8.35; O, 14.31, found: C, 71.62; H, 5.70; N, 8.36; O, 14.32. 1 H NMR (500 MHz, CDCl3)δ10.85 (s, 2H), 8.67-8.64 (m, 2H), 8.59-8.56 (m, 1H), 7.71-7.69 (m, 1H),7.56-7.52 (m, 4H), 7.16-7.03 (m, 4H), 3.87 (s, 6H), 3.64-3.60 (m, 4H), 1.47-1.44 (m, 4H), 1.20-1.15 (m, 4H), 0.78-0.75 (m, 6H).

[0043] Example 2

[0044] Synthesis of p-DPP-dimer

[0045]

[0046] Lithium tert-butoxide (4.0 g, 50 mmol) was weighed into a round-bottom flask, and the flask was purged with nitrogen three times. Then, isophthalonitrile (3.84 g, 30 mmol), intermediate 3 (4.07 g, 10 mmol), and 30 mL of tert-amyl alcohol were added. The mixture was heated to 80 °C and reacted for 10 h. After the reaction was complete, the mixture was cooled to room temperature, and 20 mL of acetic acid was added with stirring. The mixture was extracted three times with dichloromethane, and the organic layers were combined. The extract was dried over anhydrous sodium sulfate and distilled under reduced pressure to obtain the crude product. The crude product was purified by recrystallization to give 3.50 g of a red solid product (p-DPP-dimer), with a yield of 51%. MS (ESI): m / z [M] + calcd for C 40 H 38 N4O6: 670.284, found: 670.280. Elemental Analysis calcd: C, 71.63; H, 5.71; N, 8.35; O, 14.31, found: C, 71.64; H, 5.72; N, 8.34; O, 14.30. 1 H NMR (500 MHz, CDCl3) δ10.89 (s,2H), 8.47-8.43 (m, 2H), 7.72-7.69 (m, 2H), 7.56-7.53 (m, 2H), 7.19-7.13 (m,2H), 7.09-7.06 (m, 4H), 3.86 (s, 6H), 3.66-3.60 (m, 4H), 1.49-1.47 (m, 4H), 1.20-1.15 (m, 4H), 0.78-0.75 (m, 6H).

[0047] Performance testing

[0048] Two pyrrolopyrrole dione dimer fluorescent materials were dissolved in tetrahydrofuran to prepare a concentration of 1*10. -6A mol / L solution. The maximum absorption and emission peaks of m-DPP-dimer are 469 / 489 nm and 530 / 558 nm, respectively. Placing the two DPP structural units at the para position of the phenyl group causes a red shift in both the maximum absorption and emission peaks of p-DPP-dimer, located at 482 / 506 nm and 553 / 581 nm, respectively. This indicates that there is more effective conjugation of the two DPP structural units in the p-DPP-dimer molecule, leading to the spectral red shift. The Stokes shifts of the two compounds are 69 nm and 75 nm, respectively, which are greater than the Stokes shifts of DPP with common symmetrical structures.

[0049] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pyrrolopyrroledione dimer fluorescent material, characterized in that, The chemical structural formula of the pyrrolopyrroledione dimer fluorescent material is: ， 。 2. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 1, characterized in that, The process is as follows: 。 3. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 2, characterized in that, Includes the following steps: (1) Add o-methoxybenzaldehyde and 2-5 times the amount of n-butylamine to a reaction flask, add alcohol solvent, react at room temperature for 1-2 h, then add 2-4 times the amount of sodium diethyl oxaloacetate and 3-5 times the amount of acid, react at 40-80℃ for 10-20 h, after the reaction is complete, cool to room temperature, extract, combine organic layers, dry, distill under reduced pressure to obtain crude product, and purify to obtain intermediate 1; (2) Add intermediate 1 and 3 to 5 times the amount of reducing agent to the reaction flask, add a mixed solvent of ethanol and acetic acid, heat to 50 to 80°C for 2 to 4 hours, after the reaction is complete, cool to room temperature, extract, combine organic layers, dry, distill under reduced pressure to obtain crude product, and purify to intermediate 2. (3) Add intermediate 2 and 2 to 4 times the amount of triethylamine to the reaction flask, then add dichloromethane, mix well, and slowly add 2 to 4 times the amount of trimethylchlorosilane. React at room temperature for 3 to 5 hours. After the reaction is complete, extract, combine the organic layers, dry, and distill under reduced pressure to obtain crude product, which is then purified to intermediate 3. (4) Add 3 to 6 times the amount of base and 2 to 4 times the amount of aromatic cyano compound to the intermediate. Add tert-amyl alcohol to the reaction flasks separately, mix well, and then heat to 60-100℃ under nitrogen protection for 5-12 hours. After the reaction is complete, cool to room temperature, extract, combine the organic layers, dry, and distill under reduced pressure to obtain the crude product. The crude product is then purified to obtain DPP-dimer.

4. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 3, characterized in that, The alcohol solvent in step (1) is isopropanol, methanol, ethanol, n-propanol, n-butanol, n-pentanol, or n-hexanol.

5. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 3, characterized in that, The acid mentioned in step (1) is formic acid, acetic acid, propionic acid, or butyric acid.

6. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 3, characterized in that, The reducing agent in step (2) is NaBH4, zinc powder, Pd / C, or LiAlH4.

7. The method for preparing the pyrrolopyrrole dione dimer fluorescent material according to claim 3, characterized in that, The alkali mentioned in step (4) is lithium tert-butoxide, sodium tert-butoxide, NaH, or LiOH.

Images